checksum_utils.py

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# Check the NMEA sentence checksum. Return True if passes and False if failed
def check_nmea_checksum(nmea_sentence):
    split_sentence = nmea_sentence.split('*')
    if len(split_sentence) != 2:
        #No checksum bytes were found... improperly formatted/incomplete NMEA data?
        return False
    transmitted_checksum = split_sentence[1].strip()

    #Remove the $ at the front
    data_to_checksum = split_sentence[0][1:]
    checksum = 0
    for c in data_to_checksum:
        checksum ^= ord(c)

    return ("%02X" % checksum) == transmitted_checksum.upper()